Hydraulic shock absorber valving assembly



Sept. 26, 1944. G. M. MAGRUM HYDRAULIC SHOCK ABSORBER VALVING ASSEMBLY 2Sheets-Sheet 1 Filed Oct.9, 1942 Patented Sept. 26, 1944 HYDRAULIC SHOCKABSORBER VALVING ASSEMBLY Gervase M. Magrum, Buffalo, N. Y., assignor toHoudaillc-Hershey Corporation, Detroit, Mich, a corporation of MichiganApplication October 9, 1942, Serial No. 461,365 1 Claim. 27754) Myinvention relates to'hydraulic shock dampers or absorbers, andparticularly to improved valving assembly for controlling the flow ofdisplaced hydraulic fluid. 7

An important object of the invention is to provide a valving assemblycomprising a main valve adjustable to interpose a predeterminedresistance of the fluid flow between hydraulic working chambers 'in theshock absorber, and

auxiliary valving'means functioning, during slow or gradual relativemovement of the cylinder and piston to by-pass displaced fluid aroundthe main valve but which, upon more sudden or increasingpressure flow,closes so that the displaced flow must be through the main valve. Forexample, where the shock absorber is-used for controllin'gthe operationof a castoring wheel on an airplan landing gear, the auxiliary valvemeans will permit comparatively free flow of the displaced hydraulicfluid during slow or-gradual movement of the castorin'g wheel, but willshut off the free flow: during more abrupt movements of;the castorin'gwheel so that the movements of the castoring wheel will then becontrolled by the resistance to the flow of the fluid through the mainvalve.

'The main features of myinvention are embodied in the structuredisclosed on the drawings, in which 7 Figure 1 is a section on the lineII of Figure 2 of a shock absorber in which my improved valving assemblyis applied;

Figure 2 is a section on plane IIII of Fig-,

ure '1;

Figure 3 is a section similar to Figure 2 showing a modified valvingarrangement;

Figure 4 is an elevation view of the outer end of one of the pistonvanes to show relief passageway and valving means; and

Figure 5 is a side elevation of the structure on Figure 4.

Except for modified arrangement of the valving assemblyflshe structureand the shock absorber on Figures 2 and 3'is the same. It comprises thecup-shaped housing In receiving at its outer end the bearing wall I I,from which abutment walls I-2 extend-to the base of the housing, pins I3holdin'g'the walland abutments against rotational displacement withinthe housing. The bearing wall journals thepiston shaft I4 extending fromthe cylindrical piston hub I5 within the abutments I2, the hub havingvanes I6 which, with the abutment, define hydraulic working A closuremember or cover I9 is screwedinto the outer'end of the housing Ill toaxially hold the wall I I and abutments I 2in place, the wall I I andcover I9 having opposed-recesses forming a reservoir 2Il for hydraulicfluid which is fed to the working chambers through check valvecontrolled passageways 2I,*-in a manner wellknown in theart. When theshock absorberis'employed one vehicle, such asan-automobile, thehousingis usually secured to-the vehicle body'and the outer end of the pistonshaft is connected by suitable levers withthevehicle axle so that uponrelative movement between the-axle and body the piston structure will-beoperated in thehousing to displace fluid in the working chambers.Whenthe shock absorber is employed on aircraft landing gear, the shockabsorber housing may be mounted on the landing-gear'frameworkand thepiston'shaft connected by suitable levers with the castor wheel assemblyso that castoring movement of the wheel willcause oscillation of thepiston structure within the housing.

At its inner endthe pistonhub'has the wall or chamber 22 into'whichextendsaboss 23011 the housing base for affording additionalbearing support for the piston structure. Extending'outwardly throughthe piston shaft from the chamber'22 is the bore through-whichextends-the main valve structure M. Within the chamber 22 is'the valveseat body 25' of the auxiliary valve structure-A, the seat body beingsecured at substantially the middle of the chamber 23 by threadedengagement of its'flange 'portion 26 withthe piston hub to seatagainstashoulder-ZI.

The outer end of'the chamber 22 is'connected by passageways 28 and '28with the hydraulic workingchambe rs I1 and Il' respectively, while theinner end of the chamber 22 is'connected by passageways 29 and 29' withthe working chambers I8 andl8', respectively, the seatm'ember 25 beinginterposedbetween'these two sets of passageways. p

The valve seatmember 2 5 has inwardly and outwardly extending necks 30and ill thereon, coaxial therewith, and through the seat-member and thenecks "extends the bore 32, Extending through the valve seat body 25area numberof ports 33 communicating'at their end 'Withthe inner andouter ends-of'the chamber '22. Shiftable axially on the neck 30 betweenthe inner end of the body'25anda washer 34 ,oni'the neck isthe annularvalve 35 between which and "the seat is interposed a spring 36 tendingto'hold the valve'outwardly against the washer '34 for exposure of theinner ends of the passageways '33. A similar'valve 31 is mounted'on theneck working chambers to theother.

way 33 will remain open for comparatively free flow of the displacedfluid from one set of the However, under more rapid or increasedpressure flow the corresponding valve will be moved against theresistance of its spring toward its closing position to shut ofi flowthrough the passageway 33 so that the shock absorber then becomeseffective to resist further flow. V

In the arrangement shown in Figure 2, a valve plug 40, forming part ofthe main valve structure lvLseats in the outer end of the bore 32 tocontrol theresistance to the displaced fluid flow whenithepassageways 33are closed against free flow. The valve, plug has the bore 4|communicating with the bore 32 and a cross slot 42 in the valveregisters with an orifice slot 43 through the,neck, 3l. By rotationaladjustment of the valve plug the degree of exposure to flow of theorifice slot is determined for the desired resistance-to flow of thedisplaced fluid after closure of. the passageways 33; The valve plug maybe adjusted both manually and thermostatically. As. shown on Figure 2 a,helical thermostat element 44 is located within the shaft bore 24 andhasone end secured to the valve plug and its other. end secured to astem 45 extending up- ;wardly through a packing and gland assembly 46and terminating at its outer end in an adjusting lever"41.- By turningof the lever 41 the valve. plug maybe set for the desired exposure toflow of the orifice slot 43, and then during operation of the shockabsorber and change in temperature' of the hydraulic fluid thethermostat 44;- will thermostatically effect setting of the valve plugto compensate for the variation in the viscosity of. the hydraulic fluidso that the damping' orfshock absorbing characteristics of the shockabsorber may be maintained independently o f temperature variations.Upon closure of the passageways 33 by either of the valves 35 and 31,all of the displaced fluid flow must be through the orifice slot 43against the flow resistance determined bythe area of the orifice.

When a shock absorber such as that shown on Figure 2 is used forcontrolling the castoring wheel 'onan airplane landing gear, then, undernormalor comparatively slow castoring movement of the wheel, the springswill hold the aux iliary" valves open for comparatively free flow of thedisplaced hydraulic fluid, but under sudden or abnormal movements of theWheel and corresponding pressure beyond a predetermined amount, .thevalves will be closed so that the displaced fluid flow will then have tobe through theorifice 43 for dampening of further castoring movement ofthe wheel.

. The shock absorber shown in Figure 3 is adapted particularly for useon a vehicle such as an automobile. A comparatively long valve plug 48extendsentirely through the bore 32 of the valve seat member 25, theinner end of the plu having the annular groove 49 receiving an abutmentcollar 50 for abutting the inner end of the neck 30 ontheseatmember. Thevalve bore extends through the inner end portion of theplug and has theslot 52 overlapping the orifice slot 53 in the neck 3| on the seatmember for determining the orifice passageways for resisting the flow ofdisplaced hydraulic fluid when the passageways 33 are closed. 7

Where the shock absorber isused in an automotive vehicle, the body IIIwill be-secured to the chassis and the shaft to the axle, in a mannerWell understood in the art. During the compression or bound stroke ofthe shock absorber, that is during compression of the vehicle springs,

the fluid flow will be from the working chamber l8, I8 through thepassageways 29 and 29, through the orifice 53 and the valve bore 5|, andthrough the passageways 28 and 28 into the working chambers H, H. Duringrebound of the vehicle springs, the flow will be in the oppositedirection through the path just traced. In order to prevent straining ordistortion of the shock absorber under abnormal pressureduringreboundflow, a blow oiT valve 54 is provided. In the arrangement shown thisvalve receives and is slidable on the valve plug 48, and 'a spring 55interposed between the valve and a collar 56 on the outer end of thevalve plug tending to hold the 'valve seated against. the outer end ofthe neck 3| on the valve seat member 25. The valve plug has the slot 5!connecting the bore5l"with the annular space 58 between the valve plugand the valve 54 sothat abnormal rebound pressure flow exerted againstthe, blow ofivalve will cause unseating thereof for relief of thepressure until it again assumes a safe limit. Under normal reboundpressure conditions the valve 54 will remain closed. g It may also bedesirable toprovidefor relief of abnormal pressure during thecompression or bound stroke of the shock absorber. A relief passagewaymay be provided in'one of .the piston bored to provide a valve chamber59 having invanes,.as shown in Figures 4 and 5. The vane is connected bypassageway 64 with the working chamber behind the vane. Under. ordinarypres sures during, the bound stroke; the spring 62 will hold the valve6| closed, but under abnormal bound pressure flowthe. valve 6! will beopen to expose the outlet v64 for relief flow of thefluid until normalpressure conditions areaga'in reestablished. r

A vent 65 is provided for the valvechamber 59 and opens to the same sideof the wane as the passageway 64.

, For adjusting the valve plug 48, a stem 66 is coupled to the valveplug and extends to the exterior of the shaft l4 and carries theadjusting lever 61. 1 By providing 'difierent strength springs for thevalve 35 and 31 of the auxiliary valve structure A, or by setting thevalves normally at a greater or less distance away from the ends of thepassageways 33, the free flow periods through the passageways maybecontrolled as desired.

I have shown practical and eflicient embodi mentseof the features of myinvention but I do not desire to be'limited to the exact construction;arrangement and operation as shown" an'd'described as changes and:modiflcations may be made without departing from the scope of theinvention.

I claim as follows:

A valving assembly for controlling the displaced fluid in a hydraulicdamper, comprising a seat member interposed in the path of the fluidflow and having an annular body portion, a substantially central bossextending from each of opposite faces thereof, a central fluid passageextending through said bosses and connecting opposite l0 ends thereof,other fluid passages radially spaced from said bosses and extendingthrough said body

